Pathological and Microbiological Findings in Fatal Cases of Salmonellosis in Captive Bothrops Snakes in Southern Brazil

Summary

Salmonella spp. are gram-negative commensal bacteria of vertebrates, including reptiles. Infected snakes may be asymptomatic or manifest clinical disease and death, especially after stressful events. Salmonellosis was diagnosed in 10 captive snakes from the Bothrops genus. The most frequent changes were emaciation (8/10), fibrinonecrotic or granulomatous hepatitis (8/9), fibrinonecrotic or granulomatous enterocolitis (8/9), necrotic and heterophilic myocarditis (2/10), fibrinonecrotic or granulomatous pancreatitis (2/5), fibrinoheterophilic osteomyelitis (1/10), fibrinous and pyogranulomatous pericarditis (1/10) and granulomatous splenitis (1/6). Salmonella enterica was isolated from six cases. The subspecies identified were arizonae (3/6), diarizonae (1/6) and houtenae (1/6), in addition to the serotype Typhimurium (1/6). In cases without isolation, there was immunolabelling of Salmonella spp. in intestinal (3/4), hepatic (1/4) and cardiac (1/4) lesions.

Introduction

Salmonella spp. are gram-negative, aerobic and intracellular facultative bacilli of the Enterobacteriaceae family (Ministério da Saúde, 2011). Salmonellosis is a worldwide zoonotic infectious disease well known for its potential for transmission through animal feed, unprocessed agricultural products and untreated water (Fornazari and Teixeira, 2009). Asymptomatic animal carriers are an important source of infection and can excrete the bacteria after stressful events (Fornazari and Teixeira, 2009; Hardt et al, 2017).

Reptiles are natural reservoirs of Salmonella spp., and 16%–92% of snakes can be infected (Chiodini and Sundberg, 1981). Salmonella infections are usually associated with the subspecies salamae, arizonae, diarizonae and houtenae (Fornazari and Teixeira, 2009). Transmission to humans can occur via direct contact with faeces or other animal excretions, or indirectly from contaminated enclosures or fomites (Warwick et al, 2001). The main clinical signs in reptiles are anorexia, diarrhoea, weight loss and lethargy, and the most common lesions are yellowish fibrinonecrotic plaques and button-shaped ulcers in the small and large intestines, and hepatic multifocal granulomas and necrosis (Fornazari and Teixeira, 2009). Pneumonia, osteomyelitis, osteoarthritis, epicarditis, granulomatous myocarditis and liver abscesses are also frequent findings (Fornazari and Teixeira, 2009).

The aim of this study was to describe the macroscopic, microscopic, immunohistochemical and microbiological aspects of fatal cases of salmonellosis in snakes.